The Influence of Boss Welding on Residual Stress of ERW Pipe
Date:2019-10-02View:876Tags:The Influence of Boss Welding on Residual Stress of ERW Pipe
Stress of API 5CT casings in oil wells: In order to ensure that the casings enter the wells continuously, without cracking or deformation, the casings should be strong enough to withstand the external forces they are subjected to. Therefore, it is necessary to analyze the stress on the inner casing.
1) Tension
2) Extrusion force
3) Internal pressure
4) Bending force
In short, the casing in the well bears the first three forces. The stress conditions of each part are different, the upper part is under tension, the lower part is under external force, and the middle part is under less stress. In the design of casing string, the steel grades and wall thickness of casing are selected based on the above safety factors. For API standard casing, the general safety factor of tension is 1.6-2.0, the safety factor of impact resistance is 1.00-1.50, 1.125, the safety factor of internal pressure is 1.0-1.33, and the safety factor of compressive strength is 0.85 at the cement injection site. It should be emphasized that the safety factor in casing string strength design is carefully selected according to the region, formation and later oil and gas production process. He is an experienced person. Due to the different external forces applied to the upper, middle and lower parts of the casing string, the designed casing string is usually thicker or more steel grades on the upper and lower walls, while in the middle it is opposite, so it needs to be numbered. Enter the well. In most cases, the enclosure works in corrosive media. Therefore, in addition to requiring a certain degree of bonding strength, the shell is required to have good sealing performance and corrosion resistance.
The Influence of Boss Welding on Residual Stress of ERW PipeThe Influence of Boss Welding on Residua
Date:2019-10-02View:876Tags:The Influence of Boss Welding on Residual Stress of ERW Pipe
Valves, meters and flanges need to be tapped in the main pipeline during site construction of natural gas and oil pipelines. At present, it is difficult to identify the straight seam position of high frequency resistance welding pipe. Some protrusions are installed very close to the welded pipe seam. Therefore, it is very necessary to study and analyze the influence of the installation of the owner on the foundation pipeline. The distribution of residual stress on high frequency straight seam resistance welded pipeline and its effect on the original residual stress at different welding positions of bumps on pipeline were analyzed by drilling. After the bulge installed on the pipeline is much larger than that of the parent pipeline, the stress rises sharply and the longitudinal residual stress of the weld affects it.
The Conduit
The distribution of residual stress in pipeline is closely related to its welding and forming process. HFW resistance welding is to form the cross section of circular billet after rolling. The skin effect and proximity effect of high frequency current are used to make the induced current highly concentrated at the edge of the opening edge. The pipe makes the temperature rise rapidly to the welding temperature, and the extrusion roll is extruded. The dimension and hydraulic test after welding are both important processes leading to the value of axial residual stress greater than that of circumferential residual stress. After high frequency welding, on-line heat treatment improves the structure and properties of the weld and heat affected zone, thus reducing the residual stress near the weld and the weld. The total residual stress on ERW pipeline is small, and the residual stress is larger than the circumferential residual stress. the maximum axial and circumferential yield strength of ERW pipeline is about 38% and 29% of the base metal. The residual stress of longitudinal weld near the pipe is lower than that of the pipe body. The axial and circumferential variation ranges from 24.5% to 33.6% and 16.4% to 21.5% of the base metal yield strength, with stress concentration.
